1. Field of the Invention
This invention integrates electrostatic (fields) and magnetic (flux) phenomenologies, and mechanical (sieve) techniques, into a programmable and adaptable filtration system for the removal of contaminants from various hydrocarbon and organic fluids to refresh their functionality and extend their useful life in the commercial marketplace. This invention focuses upon a fluid filtration system design that is: economical to manufacture, use and maintain; easily adapted to different fluid properties and contaminant characteristics; safe and easy to use in the workplace; and provides both health and environmental advantages.
2. Discussion of the Prior Art
A plethora of concepts, methods and devices have been identified to remove particulate contaminants from hydrocarbon and organic fluids to extend their useful life, or increase the reliability of precision machinery, or improve the efficiency of combustion. Basic structures for removing finite particulates from fluids by mechanical, magnetic and electrostatic means are documented in the following prior art examples:
______________________________________ Barrington 5,242,587 9/93 Dawson 4,961,845 10/90 Scott 4,941,959 6/90 Eggerichs 4,879,045 11/89 Pera 4,716,024 12/87 Mintz 4,634,510 1/87 Nozawa 4,620,917 11/86 Kyle 4,604,203 8/86 Thompson 4,594,138 6/86 Collins 4,303,504 12/81 Stegelman 4.285,805 8/81 Robinson 4,254,393 3/81 Wolf 4,238,326 12/80 Watson 4,190,524 2/80 Noland 4,025,432 5/79 Davies 3,655,530 4/72 Van Vroonhoven 3,484,367 12/69 Lochmann 3,398,082 8/68 Waterman 3,393,143 7/68 Miyata 3,349,143 10/67 Griswold 3,252,885 5/66 ______________________________________
It is evident from the prior art that the use of mechanical, magnetic and/or electrostatic filtering can effect the performance and useful life of various hydrocarbon and organic based fluids. However, efficient and cost effective mobile filtration systems are not readily evident in the commercial marketplace.
The effectiveness of mechanical fluid filters, such as sieves (e.g., paper, cloth and meshes) is limited by the size of the passageway through the media. This limitation, even with current technology, restricts their capture effectiveness to particulates with diameters larger than about 5 microns, nominally less than 30% of the contaminant population. As an example, U.S. Pat. No. 4,604,203 to Kyle evidences this significant disadvantage, as well as a limited fluid throughput that is economically imprudent in the commercial marketplace.
To achieve the next filtration level, electrostatic filters are proposed. These filters impart an electrical charge to the contaminant particulates, including sizes much less than a micron, that causes these "fines" to attract one another to form "straws" that are sufficiently large to be captured on and in filtration media placed between alternately charged porous metal plates.
The electrostatic filter constructs disclosed in the references to Dawson (U.S. Pat. No. 4,961,845), Lochmann (U.S. Pat. No. 3,398,082) and Van Vroonhoven (U.S. Pat. No. 3,484,367) fail to employ magnetic fields and suffer reduced particulate removal efficiency (15-18%). Additionally, the construct shown in Dawson does not provide space for the accumulation of particulates which significantly reduces the lifetime (i.e., arcing) of the filter prior to disposal (vice reuse) and appears to be applicable only to the removal of large particulates.
The combination of electrostatic fields and magnetic flux is shown by the references to Miyata (U.S. Pat. No. 3,349,143), Robinson (U.S. Pat. No. 4,254,393) and Thompson (U.S. Pat. No. 4,594,138). Although the magnetic flux accelerates the charging of the particulates by the electrostatic fields, it is not clear that the references to Miyata or Robinson have demonstrated any filtering capabilities. All three suggest throw-away (versus reuse) filters, but only the Thompson reference suggests a limited system construct. Thompson's construct requires that the filter become a part of a hydraulic or dielectric fluid system, provides no obvious way to regulate voltage and current for changing fluid conditions, and provides no spacers for the accumulation of trapped particulates thereby shortening the economic life of the filter. The reference to Thompson also presents a fixed plate configuration suggesting that separate filters must be manufactured for different fluids.
The reference to Barrington (U.S. Pat. No. 5,242,587) comes closest to presenting a mobile stand-alone fluid filtration system. However, this design fails to address the safety, economics and usability requirements of the commercial marketplace. No discernable consideration is given to preventing access to the electrostatic voltage during use or maintenance, and the suggested plastics are not amenable to high temperature (e.g. , cooking oil) or corrosive solvents (e.g., tetrachlorathylene perclorethylene) thereby precluding use on the broad family of hydrocarbon and organic liquids. Additionally, the Barrington reference does not specify how voltage and current are tuned to either the fluid or the contaminant characteristics, which implies separate filter manufacturing for each fluid with the attendant increased costs resulting therefrom. Barrington also suggests that noncircular plate perforations (e.g., square, rectangular, triangular) are acceptable. However, it has been experimentally proven that corners and sharp edges expand to cause bypass under pressure and support the aggregation of captured particulate to produce arcing which shorts out the filters' efficiency and requires frequent cleaning. The second most significant economic drawback to this construct is the implementation of the electrical distribution in the electrostatic filter. Polyvinylchloride stand-offs are hand connected to create a vertical plurality of alternately charged plates, and must be totally disassembled for maintenance. This is a labor intensive cost driver for both manufacturing and maintenance. In addition, the use of PVC cut pipe is inadequate in that it will dissolve in some hydrocarbon fluid environments and deform at elevated temperatures.
Therefore, while many embodiments of electrostatic fluid filters are known, they are for the most part, commercially ineffectual, expensive to use and maintain, and not easily adapted to changing fluid requirements without considerable time and labor.